public class MergeSortNor {
    public static void mergeSort(int[] array){
        int gap = 1;
        while (gap < array.length) {
            for (int i = 0; i < array.length; i++) {
                int left = i;
                int mid = left + gap - 1;
                if (mid >= array.length) {
                    mid = array.length-1;
                }
                int right = mid + gap;
                if (right >= array.length) {
                    right = array.length-1;
                }
                merge(array,mid,left,right);
            }
            gap *= 2;
        }
    }

    private static void merge(int[] array, int mid, int left, int right) {
        int s1 = left;
        int e1 = mid;
        int s2 = mid+1;
        int e2 = right;
        int[] tmpArr = new int[right-left+1];
        int k = 0;

        while (s1 <= e1 && s2 <= e2) {
            if (array[s1] <= array[s2]) {
                tmpArr[k++] = array[s1++];
            }else {
                tmpArr[k++] = array[s2++];
            }
        }

        while (s1 <= e1) {
            tmpArr[k++] = array[s1++];
        }
        while (s2 <= e2) {
            tmpArr[k++] = array[s2++];
        }

        for (int i = 0; i < k; i++) {
            array[i] = tmpArr[i];
        }
    }
}
